Neuroendocrine correlates of the critical day length response in the Soay sheep
Neuroendocrine correlates of the critical day length response in the Soay sheep
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索伊羊临界日长反应的神经内分泌相关性
DOI：
10.1111/jne.12631
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发表时间：
2018
影响因子：
3.2
通讯作者：
H. Dardente
中科院分区：
文献类型：
--
作者：
D. Hazlerigg;D. Lomet;G. Lincoln;H. Dardente
在哺乳动物中，褪黑激素是负责生理学的季节性生理周期与太阳年同步的激素。褪黑激素由松果体分泌，其特征反映了夜间的持续时间，并通过垂体结节部（PT）中的褪黑激素反应细胞起作用，进而调节下丘脑甲状腺激素状态。最近的模型表明，褪黑激素在PT中的作用主要取决于眼睛缺失3（Eya 3）表达的日长依赖性变化，Eya 3是促甲状腺激素β亚基（Tshβ）基因转录的共激活因子。根据该模型，短光周期抑制Eya 3，从而抑制Tshβ表达，而长光周期产生相反的效果。支持该模型的研究依赖于光周期的阶跃变化（从8至16小时光照/24小时），并且没有将Eya 3和Tshβ表达变化的光周期敏感范围与相关下游分子和内分泌反应的光周期敏感范围进行比较。因此，我们在Soay绵羊中进行了“临界日长”实验，其中将适应8小时光照/24小时（SP）的动物暴露于范围为11.75至16小时（LP）的增加的光周期范围内，然后评估PT，下丘脑和激素输出水平的反应。尽管Eya 3和Tshβ均显示出预测的SP与LP差异，但它们对该范围内的中间光周期的反应完全不同，并且在个体动物水平上，未观察到明确的Eya 3-Tshβ关系。这一结果与PT中EYA 3作用的简单共激活因子模型不一致。在Tshβ-dio 2和dio 2-睾酮关系方面也观察到了进一步的下游非线性层。我们的结论是，在光周期的渐进变化的转导到内分泌输出的过渡是一个多步骤的信号级联哺乳动物神经内分泌系统内的一个紧急属性。
In mammals, melatonin is the hormone responsible for synchronisation of seasonal physiological cycles of physiology to the solar year. Melatonin is secreted by the pineal gland with a profile reflecting the duration of the night and acts via melatonin‐responsive cells in the pituitary pars tuberalis (PT), which in turn modulate hypothalamic thyroid hormone status. Recent models suggest that the actions of melatonin in the PT depend critically on day length‐dependent changes in the expression of eyes absent 3 (Eya3), which is a coactivator for thyrotrophin β‐subunit (Tshβ) gene transcription. According to this model, short photoperiods suppress Eya3 and hence Tshβ expression, whereas long photoperiods produce the inverse effect. Studies underpinning this model have relied on step changes in photoperiod (from 8 to 16 hours of light/24 hours) and have not compared the sensitive ranges of photoperiods for changes in Eya3 and Tshβ expression with those for relevant downstream molecular and endocrine responses. We therefore performed a “critical day length” experiment in Soay sheep, in which animals acclimated to 8 hours of light/24 hours (SP) were exposed to a range of increased photoperiods spanning the range 11.75 to 16 hours (LP) and then responses at the level of the PT, hypothalamus and hormonal output were assessed. Although Eya3 and Tshβ both showed the predicted SP vs LP differences, they responded quite differently to intermediate photoperiods within this range and, at the individual animal level, no clear Eya3‐Tshβ relationship could be seen. This result is inconsistent with a simple coactivator model for EYA3 action in the PT. Further downstream layers of nonlinearity were also seen in terms of the Tshβ‐dio2 and the dio2‐testosterone relationships. We conclude that the transduction of progressive changes in photoperiod into transitions in endocrine output is an emergent property of a multistep signalling cascade within the mammalian neuroendocrine system.
绵羊每年繁殖节律的光周期同步：季节特定时间线索的识别。
影响因子：
3.6
作者：
Woodfill,CJ;Wayne,NL;Moenter,SM;Karsch,FJ
通讯作者：
Karsch,FJ
光周期历史和不断变化的褪黑激素模式可以决定母羊对日照长度的神经内分泌反应。
DOI：
10.1530/jrf.0.0800159
发表时间：
1987
期刊：
Journal of reproduction and fertility
影响因子：
--
作者：
Robinson,JE;Karsch,FJ
通讯作者：
Karsch,FJ